LED lighting - interference issues
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Summary
Switched mode power supplies that drive LED navigation lights have been found to produce interfering signals which affect VHF communications on vessels. These lights have been found to comply with the EMC limits given in IEC 60945 (Maritime navigation and radiocommunication equipment and systems - General requirements – Methods of testing and required test results).
The cause and effect of the problem are well explained here: FAQ - LED Radio Interference Issues
The issue is being addressed at ITU, IEC, CISPR and RTCM as described below.
Timeline
- October 2019: At the IEC Technical Committee 80 Plenary Meeting a Preliminary Work Item (PWI) was created on the subject of LED navigation lights. RTCM SC137 proposed that a new proposal should be submitted when RTCM SC137 has a Committee Draft available of their related standard (within one year approx); this approach was endorsed by CIRM.
- June 2019: RTCM established Special Committee 137 (SC137) to develop a standard on ‘Electromagnetic Compatibility Requirements for Light Emitting Diode Devices and other Unintentional Emitters Located Near Shipboard Antennas’.
- May 2019: ITU-R WP 5B drafted a liaison statement to CISPR and ITU-R WP 1A (Spectrum engineering techniques) requesting to be informed of the progress of the work of WP 1A and CISPR regarding the assessment of the impact of unwanted radio frequency energy generated by non-radiocommunication equipment to radiocommunication service. The liaison statement suggested that the CISPR 25 Class 5 automotive standard for EMI levels and distance separations may be a useful reference for a new standard. The liaison statement was copied to IMO and CIRM for information.
- 7th January 2019: Email from Kim Fisher:
There was some progress at the CISPR plenary in October. They decided to start an amendment to CISPR 15 and issue a Questionnaire on topics to be considered. They also decided to start work on a new report TR CISPR 30-3 on test methods for built-in LED convertors which is good news because that is where the real problem lies. I have not seen the Questionnaire yet. I will chase it up.
We will have to await to see if France or whatever will pick up the new work item in IEC.
If that does not happen a simpler approach in IEC would be to consider a PAS (Publicly Available Specification) on navigation lights. If all that needs to say is use the CISPR 25 Class 5 limits the PAS should be straight forward to write.
- 3rd January 2019: John Shaw raises the following related issue in an email exchange on this issue:
CENELEC studies have shown the impact of component ageing in LED products to be very severe by allowing high levels of RF noise to leak back on to mains wiring, which then causes higher operating temperatures within the power conversion stage components, particularly electrolytic capacitors, of any connected devices. Thus a vicious circle can develop in which component degradation in one device injects RF noise on to mains lines, which then causes rapid component ageing in other LED units and electrical products, and so on.
- 13th December 2018: At the CIRM Annual Technical Workshop, the IEC TC 80 Secretary reported that the preliminary work item at IEC needs an administration to take it on, and that France had been approached in this regard.
- 6th November 2018: Email from Martin Bransby, Head of Research & Development, General Lighthouse Authorities of the UK & Ireland:
This isn’t an issue with LEDs as such, it is the way that they are driven. The drivers use switch mode power supplies (SMPS) which cause the problem. SMPS have been around for a few decades now, so the problem has always been there. Manufacturers have made the SMPS less noisy over the years and thus cause less interference; however, a proliferation of cheap “Chinese” SMPS which drive the plethora of LED lights these days has made the problem more prevalent.
The old adage “buy cheap, buy twice” fits here. My advice would be for ships’ fitters to look at data sheets before replacing filament lamps with LED equivalents.
There is unlikely to be any IALA advice as this is a shipside problem. I would look to the IMO here.
- October 2018: Response from IEC TC 80 to ITU-R WP 5B (Document 5B/584), considered at the November 2018 meeting of WP 5B, states the intention of IEC TC 80 to generate a new preliminary work item concerning requirements for LED navigation lights and their installation.
- September 2018: CIRM is asked to circulate the below safety alert to CIRM members by the US Coast Guard:
The USCG is investigating interference to maritime radios from LED lighting. The below link to the safety bulletin outlines a suggested testing method, but if you select a weak weather broadcast with the LED lights off, then turnItalic text the LED lights/devices on, you can note if the weak station is interfered with. The interference desensitizes the VHF and the AIS receivers to the point where they will not receive properly. It does not seem to matter who the LED manufacturer is at this point, as all LED lighting and devices may show potential interference. Please let the USCG know at Russell.s.levin@uscg.mil if you do find the interference along with the manufacturer and model of the lighting involved.
Let us enlighten you about LED lighting!
- July 2018: Response from CISPR to ITU-R WP 5B (Document 5B/562) on ‘EMI standards for LED lighting’ considered at the November 2018 meeting of WP 5B, observes that IEC 60945 is much more suited for civil maritime applications than CISPR 15, and that CISPR 25 may be applicable for maritime lighting equipment if the length of the boat is < 15m. Document 5B/562 recommends that in a future amendment of CISPR 15 the scope shall be clarified such that lighting equipment for maritime applications and other IEC application domains is clearly excluded. It further recommends that Both IEC 60945 and CISPR 25 should be reviewed regarding the suitability of limits and associated test methods and conditions that apply for electrical or electronic equipment that may be located in the proximity of receiving antennas of essential or critical radio systems.
- June 2018: Liaison statement from ITU-R WP 5B to CISPR H & F, and IEC TC 80 (Annex 30 to Working Party 5B Chairman's Report Document 5B/538), raises the issue that LED lighting has been identified as having the potential to become a major source of electromagnetic interference (EMI) even if it is compliant with current EMC standards. Actions proposed in the liaison statement were that the level of radiated disturbances should be reviewed and revised in CISPR 15:2013/A1:2015 or CISPR 25 Class 5 (due to the possibility of installation of LED lighting in close proximity to critical GNSS radio navigation, GMDSS VHF communications and AIS antennas). Annex 1 of document 5B/498 (see above) is attached to this liaison statement.
- May 2018: Contribution 5B/498 from France to ITU-R WP 5B ('Electromagnetic disturbance due to lighting using LED technology'), considered at the May 2018 meeting of WP 5B, describes problems encountered during inspections of GMDSS radio installations and AIS due to electromagnetic disturbances generated by various lighting using LED technology. The report in Annex 1 is entitled: 'Report on LED interference on board vessel'. This report resulted from inspections of GMDSS equipment and AIS performed by the National Frequencies Agency (ANFR) on board ships, during which crews and shipowners reported problems regarding reception on VHF frequencies (radiotelephone / DSC and AIS) when navigation lights are switched on or during the use of other system of lighting (i.e. searchlights). The report lists observations of electromagnetic disturbances caused by LED navigation lights witnessed by an ANFR surveyor. The report notes that both field and laboratory measurements of radiation resulting from the navigation lights comply with IEC 60945 in the VHF band. The report states that the CISPR 15 2013 + IS1: 2013 + IS2 : 2013 standard sets out limit values of radiated disturbances that are incompatible with maritime safety. The report suggests that the CISPR and IEC standards relating to LED technology should be revised.
Related Standards
- IEC 60945:2002/COR1:2008 Maritime navigation and radiocommunication equipment and systems - General requirements – Methods of testing and required test results
- CISPR 15:2013/A1:2015 & CISPR 15:2018 - Limits and methods of measurement of radio disturbance characteristics of electrical lighting and similar equipment
- CISPR 25:2016 - Vehicles, boats and internal combustion engines - Radio disturbance characteristics - Limits and methods of measurement for the protection of on-board receivers
